For centuries, Venice has fought a losing battle against 'Acqua Alta'—exceptional high tides driven by Adriatic winds, storm surges, and lunar cycles. To protect the historic city without permanently severing its marine ecosystem or maritime trade, engineers constructed the MOSE project (Modulo Sperimentale Elettromeccanico). Installed at the three inlets connecting the Venetian Lagoon to the sea—Lido, Malamocco, and Chioggia—MOSE consists of 78 massive steel gates resting invisibly on the seabed.
Under normal weather conditions, these hollow yellow gates remain filled with seawater, lying flat in heavy concrete housing structures buried in the seafloor. This configuration keeps the inlets completely open, allowing commercial shipping traffic to pass and natural tides to flush the lagoon daily. However, when tides are predicted to rise more than 110 centimeters above normal, technicians initiate the barrier's rising sequence.
Compressed air is pumped into the hollow gates, forcing the trapped seawater out through lower openings. As the water leaves, buoyancy takes over. The gates naturally swing upward on massive underwater hinges, rising at a 45-degree angle to break the water surface.
Together, the gates form a continuous wall that blocks the incoming sea surge. Once the high tide recedes, the process is reversed: seawater is allowed to flood back into the gates, causing them to sink back into their concrete trenches. Successfully deployed for the first time in October 2020, MOSE relies on Archimedes' principle rather than complex motors to keep one of the world's greatest architectural treasures dry.